College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, PR China.
Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703 HB Wageningen, The Netherlands; Department Biomedical Engineering, University of Groningen and University Medical Center Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands.
J Colloid Interface Sci. 2014 Sep 15;430:40-6. doi: 10.1016/j.jcis.2014.05.029. Epub 2014 Jun 2.
The interaction between protein and soluble organic matter is studied through layer-by-layer assembly of lysozyme (LSZ) and purified Aldrich humic acid (PAHA) at a solid surface (2-D) and in solution (3-D). By bringing a silica surface in alternating contact with solutions of LSZ and PAHA a layer-by-layer LSZ-PAHA assembly is formed. At pH 5 the negative charge density of PAHA is about 3 times that of the positive LSZ; the layers of LSZ and PAHA are stable and the adsorbed amounts decrease with increasing ionic strength. The mass ratios PAHA/LSZ in the layers depend on the ionic strength; K(+) incorporation is relatively large (∼25%) when PAHA is the outer layer of the assembly. At pH 6 and 8, and moderate ionic strength (0-100 mmol L(-1) KCl) the assembly is accompanied by partial solubilization of positive LSZ by the much more negative PAHA followed by desorption of the complex. The solubilization increases with increasing pH, and decreases with increasing KCl concentration. At 400 mmol L(-1) KCl the electrostatic interactions are so well screened that the assembly is no longer accompanied by layer erosion. Assembly of PAHA and LSZ in solution is also investigated at pH 5 and 5 mmol L(-1) KCl. The PAHA/LSZ mass ratio at the iso-electric point of the assembly depends on the order of the addition. When LSZ is added to the negative assembly K(+) is incorporated in the complex, but when PAHA is added to the positive assembly PAHA and LSZ neutralize each other.
在固相中（2-D）和溶液中（3-D）通过溶菌酶（LSZ）和纯化的 Aldrich 腐殖酸（PAHA）的层层组装来研究蛋白质和可溶性有机物之间的相互作用。通过使二氧化硅表面与 LSZ 和 PAHA 的溶液交替接触，形成了层层 LSZ-PAHA 组装体。在 pH 5 时，PAHA 的负电荷密度约为正 LSZ 的 3 倍；LSZ 和 PAHA 层是稳定的，随着离子强度的增加，吸附量减少。层中的 PAHA/LSZ 质量比取决于离子强度；当 PAHA 是组装体的外层时，K(+)的掺入相对较大（约 25%）。在 pH 6 和 8 以及中等离子强度（0-100mmolL(-1)KCl）下，组装伴随着更多负 PAHA 对正 LSZ 的部分溶解，随后是复合物的解吸。溶解度随 pH 的增加而增加，并随 KCl 浓度的增加而降低。在 400mmolL(-1)KCl 下，静电相互作用得到了很好的屏蔽，组装不再伴随着层侵蚀。在 pH 5 和 5mmolL(-1)KCl 下也研究了 PAHA 和 LSZ 在溶液中的组装。组装的等电点处的 PAHA/LSZ 质量比取决于添加顺序。当 LSZ 被添加到负组装体中时，K(+)被掺入复合物中，但当 PAHA 被添加到正组装体中时，PAHA 和 LSZ 相互中和。
